'screen setup
 mode 2: cls
 
 'startscreen
 print "simple scope"
 print "uses GP26 analog input, and samples at 100kHz"
 print "to demonstrate PSRAM on RP2350B platform"
 print "cursor keys zoom and pan the displayed data"
 print "press any key to start sampling"
 do : loop while inkey$=""
 
 'pan-zoom
 pan=0
 zoom=1
 points=100000
 rate=100000
 
 'the data array
 dim a(points) as float
 
 'the video array
 dim y(319) as integer       'will be adc samples
 dim x(319) as integer
 for i=0 to 319:x(i)=i:next  'coordinates x
 
 'the adc taking samples
 cls : print "sampling"
 adc open rate,1
 adc start a(),,,,100,200 'and scaling between 100 and 200
 pause points/rate*1000
 cls : print "done    "
 
 do

   'display part of array using vectors
   for i=0 to 319: y(i)=a(i*zoom+pan) : next
   line graph x(),y(),rgb(green)
   
   'display the memory (what data is viewed )
   line 0,90,319,90,3,rgb(green)
   xstart=320*pan/points
   sze=320*320*zoom/points
   line xstart,90,xstart+sze,90,3,rgb(red)
   
   do
     k=asc(inkey$)
   loop while k=0
   
   select case k
     case 128
       zoom=zoom+1
       if zoom>20 then zoom=20
       cls
     case 129
       zoom=zoom-1
       if zoom<1 then zoom=1
       cls
     case 131
       pan=pan+zoom*160
       if pan>points-zoom*320 then pan=points-zoom*320
       cls
     case 130
       pan=pan-zoom*160
       if pan <0 then pan=0
       cls
     case 32
       save compressed image "scrn.bmp"
   end select  
   
 loop